Outgasing of Reed Relays in Ultra High Vacuum

There is always the possibility of outgasing of any package in a high vacuum, whether that package is plastic or otherwise. Products designed for high reliability applications, expecially for use in outer space, are tested for many things, but I am not sure that they are specifically tested for outgasing. I suggest that you contact the manufacturer and ask them if their devices have been tested or characterized for outgasing and how much outgasing is expected.

For reed relays I would expect that outgasing would not be a problem for the relay itself, but I do not know about your system so do not know the effects of outgasing upon your system.

- Nick Gray

Hi Thomas,

Its been two decades since I worked with any high vacuum instruments. My memory from back then was that pretty much all plastics , resins etc outgassed, particularly the sort that is made by mixing two components (eg casting resins) , which is how I imagine those reed relays are manufactured.

Even just machining grade plastics (HDPE,PP,delrin) have additives that may outgas.

Printed circuit board epoxy will also outgas. I presume you are using teflon PCB's?

Nylons and some other plastics can absorb upto 2% moisture.

Pure teflon is OK.

We used a product called "torr-seal"  it comes in two tubes , looks like araldite but gritty. You use it seal up all the potential outgassing bits, and for assembling stuff (Like lenses onto lasers tubes.) You can make your own feedthroughs by poking solid copper wires through a hole, then gooping torr-seal into the gap.

See http://www.pchemlabs.com/product.asp?pid=2619

In your case you could just paint the relay with torr-seal after soldering it (bit tricky getting under the package) , torr-seal is not particularly runny.

They have some waxes on the page too, possibly could wax impregnate your parts? (I have no personal experience of this though)

Note you obviously need to thoroughly degrease your parts, and bake out / pump down any moisture before assembly.

Hope this helps.

First establish what your outgassing requirements are. Then contact the manufacturer and figure out what the plastic case is made out of, then  go to http://outgassing.nasa.gov and find your material (they have most of them).